You will need to transplant your seedling into a bigger pot or into the ground when the plant is approximately 5-6 inches tall and before it gets rootbound.  Stick a pencil or other slim, dull object into the drain hole in the bottom and gently push the soil with plant out the top of the container.  You may also run a dull table knife around the inside of the can against the can wall to loosen the plant for removal.